1. Field of the Invention
The present invention relates to a disposable indexable cutting insert, particularly to a cutting insert such as is adapted for being detachably mounted on a tool holder and for cutting a work piece. Cutting inserts of the present invention are generally made of a cemented metal carbide such as tungsten carbide and are formed by pressing techniques after which the pressed articles are sintered. The cutting insert of the present invention has been found to be particularly useful in the machining of titanium.
2. Description of the Prior Art
Disposable indexable cutting inserts are known in the art. Patents of general interest depicting such inserts include U.S. Pat. Nos. 4,411,564; 4,566,827; and 4,659,264. Another example in U.S. Pat. No. 4,681,485 wherein in FIGS. 6 to 8 a typical disposable indexable cutting insert is depicted which is particularly useful with an end mill cutting tool. The specific configuration and improved operating parameters of the insert of FIGS. 6 to 8 are discussed in detail in the U.S. Pat. No. 4,681,485 and will not be repeated herein except to note that such insert includes a curved cutting edge which increases the wear and life of the tool before it is necessary to index the insert. In addition, the opposed sides of the insert fall away from a respective cutting edge at an angle of about 30.degree. to the vertical so that the sides can be firmly seated in a 60.degree. conical seat formed in the cutter body. An effort to improve this insert has been made by including a 45.degree. chamfer at the upper surface of the insert adjacent the sides contiguous to and between the cutting edges. However, the 45.degree. chamfer creates an area of weakness in the form of a sharp corner at the intersection of the cutting edge and the 45.degree. chamfered corner edge. In addition, a further area of weakness is provided by the 45.degree. chamfer at 60.degree. to the face of the cutting edge; that is, at a 60.degree. included edge angle. Further, the 45.degree. chamfer corrupts a portion of the cutting edge the effect of which is to decrease the length of the cutting edge.
It is highly desirable to provide an improved disposable indexable insert. It is also desirable to provide a relatively strong insert having a smooth continuous transition along a curved cutting edge between such edge and a radiused corner edge. It is further desirable to provide a relatively strong indexable insert by virtue of having a radiused corner edge at a relatively larger included edge angle. It is also desirable to increase the length of a curved cutting edge of an indexable insert.